既有居住建筑附属地下换热站降噪研究

为了降低既有建筑附属用房产生的噪声对居民生活的影响、改善居住建筑声环境,对既有居住建筑附属用房地下换热站的噪声源以及噪声传播途径进行了分析;以既有居住建筑地下换热站室内噪声实测数据为基础,对室内环境的声学特征进行分析。在综合考虑居民的健康和舒适的基础上,提出了针对该附属用房的降噪处理改造设计方案。经过改造后的空间噪声明显降低,空间声环境指标达到标准要求,有效地改善了居住建筑的声环境。文中提出的改造设计方案为制定民用建筑附属用房声学设计标准提供了技术支撑。     

Substrate noise isolation improvement in a single-well standard CMOS process

This work describes a fully CMOS compatible methodology, which makes available a pseudo deep n-well in single-well standard CMOS process. The proposed method is based on mask manipulation to accommodate the field implant p-type region into the n-well, and does not require any additional masks or modification in the CMOS process flow. According to the experimental results, the floating NMOS made available by the methodology shows a reduction in the threshold voltage, which implies a slight improvement in its performance, when compared with its standard NMOS counterpart. It was also experimentally demonstrated up to 3 GHz, that the guard-ring field implant/pseudo deep n-well proposed structure improves substrate noise isolation when compared to the classical p+ guard-ring, with a maximum improvement above 20 dB for low frequencies and a minimum of 4 dB at 3 GHz.     

Developing electrochemical measurements in order to assess anti-corrosive coatings more effectively

The aim of this project was to check reproducibility of results obtained using NOCS (no connection to the substrate) arrangement of the electrochemical noise method (ENM). NOCS involves taking measurements from three nominally identical areas on the coated surface. Thus, no electrical connection to substrate is required. In practice the areas are not identical and various arrangements for connection of the three cells were tried to see if the individual areas could be separated out and whether the individual resistances could be computed. Also different ways of calculating the R_n (noise resistance) and R_sn (spectral noise resistance) parameters were attempted to see which one gave the best comparison with the more standard EIS measurements. The maximum entropy method was recognized to be the most useful for comparison with EIS, as well as for graphic evaluation of results. Regarding distinguishing three areas using different connection arrangements, it was possible to identify the situation when one of the three values was different to the other two. However further experiments are needed before it will be possible to confidently assign an R_n value to each individual area.     

Simultaneous nitrification and denitrification with electricity generation in dual‐cathode microbial fuel cells

BACKGROUND: Nitrogen removal using microbial fuel cells (MFCs) is of great interest owing to the potential benefits of bioenergy production. In this study, simultaneous nitrification and denitrification in dual‐cathode MFCs was investigated. RESULTS: The dual‐cathode MFCs investigated were capable of generating electricity and removing nitrogen, influenced by operating methods, nitrogen loading rates and external resistance. Depending on the ammonium concentration in the anode chamber, 84–97% of the ammonium nitrogen was removed via nitrification in the aerobic cathode. The removals of nitrate and total nitrogen were relatively low (～50%) at the influent ammonium concentration of 80 mg NH₄⁺‐N L^?1, but were significantly improved to more than 90% at a lower ammonium input (40 and 20 mg NH₄⁺‐N L^?1). When the electrode couples were electrically connected for different purposes, with high power output from the anode/aerobic cathode and high current generation from the anode/anoxic cathode, nitrogen removal was also improved. An investigation of aeration suggested that factors other than carbon supply, possibly inefficient reactor configuration, also limited the performance of the developed MFC. CONCLUSION: The experimental results demonstrated that the proposed pathway was feasible with effective nitrogen and organic removal. This study provided valuable information for the further development of a continuously operated dual‐cathode MFC system. Copyright © 2011 Society of Chemical Industry     

GE水煤浆气化锁斗程序改造

对合成氨厂煤气化开车以来遇到的锁斗运行问题进行论证,通过对其控制程序的改造,保证气化炉的正常排渣。     

Effect of noise on comfort in open-plan offices: application of an assessment questionnaire

Abstract

Open-plan offices account for 60% of French office workspaces. The noise levels recorded in this type of environment are much lower than those encountered in industrial workplaces. Nevertheless, surveys show that noise is considered by employees as the main source of discomfort. A first questionnaire dedicated to noise discomfort was produced in 2013 and tested on a panel made up of 217 people working in 7 French companies. Today, it also makes it possible to address the issues of fatigue related to ambient sound, but above all, the survey aims to study the differences in how ambient noise is perceived depending on the type of open-plan office. On the basis of that new version, a second survey has been conducted in 23 open-plan offices, making it possible to collect the responses from 617 employees. Most of the results of the first survey have been confirmed, with an increase in the significance of the statistical analyses. Moreover, French Standard NF S 31-199, which is currently being drafted, establishes a typology of open-plan office spaces according to the types of work done in them. Based on this typology, it appears that when dealing with the impact on noise on workers, a distinction has to be made between the types of open plan offices.

Practitioner Summary: Surveys conducted in open-plan offices show that noise is considered by employees as the main source of discomfort even if the noise recorded in this type of environment is not hazardous. This work presents the result of a large survey dedicated to noise discomfort conducted in 23 open-plan offices.     

Multi-scale noise estimation for image splicing forgery detection

Noise discrepancies in multiple scales are utilized as indicators for image splicing forgery detection in this paper. Specifically, the test image is initially segmented into superpixels of multiple scales. In each individual scale, noise level function, which reflects the relation between noise level and brightness of each segment, is computed. Those segments not constrained by the noise level function are regarded as suspicious regions. In the final step, pixels appears in suspicious regions of each scale, after necessary morphological processing, are marked as spliced region(s). The Optimal Parameter Combination Searching (OPCS) Algorithm is proposed to determine the optimal parameters during the process. Two datasets are created for training the optimal parameters and to evaluate the proposed scheme, respectively. The experimental results show that the proposed scheme is effective, especially for the multi-objects splicing. In addition, the proposed scheme is proven to be superior to the existing state-of-the-art method.     

Advanced daytime polysomnographic preprocessing: A versatile approach for stream-wise estimation

The enhancement of monitoring biosignals plays a crucial role to thrive successfully computer-assisted diagnosis, ergo the deployment of outstanding approaches is an ongoing field of research demand. In the present article, a computational prototype for preprocessing short daytime polysomnographic (sdPSG) recordings based on advanced estimation techniques is introduced. The postulated model is capable of performing data segmentation, baseline correction, whitening, embedding artefacts removal and noise cancellation upon multivariate sdPSG data sets. The methodological framework includes Karhunen–Loève Transformation (KLT), Blind Source Separation with Second Order Statistics (BSS-SOS) and Wavelet Packet Transform (WPT) to attain low-order, time-to-diagnosis efficiency and modular autonomy. The data collected from 10 voluntary subjects were preprocessed by the model, in order to evaluate the withdrawal of noisy and artefactual activity from electroencephalographic (EEG) and electrooculographic (EOG) channels. The performance metrics are distinguished in qualitative (visual inspection) and quantitative manner, such as: Signal-to-Interference Ratio (SIR), Root Mean Square Error (RMSE) and Signal-to-Noise Ratio (SNR). The computational model demonstrated a complete artefact rejection in 80% of the preprocessed epochs, 4 to 8 dB for residual error and 12 to 30 dB in signal-to-noise gain after denoising trial. In comparison to previous approaches, N-way ANOVA tests were conducted to attest the prowess of the system in the improvement of electrophysiological signals to forthcoming processing and classification stages.     

Reduction of quantization noise via periodic code for oversampled input signals and the corresponding optimal code design

This paper proposes to reduce the quantization noise using a periodic code, derives a condition for achieving an improvement on the signal to noise ratio (SNR) performance, and proposes an optimal design for the periodic code. To reduce the quantization noise, oversampled input signals are first multiplied by the periodic code and then quantized via a quantizer. The signals are reconstructed via multiplying the quantized signals by the same periodic code and then passing through an ideal lowpass filter. To derive the condition for achieving an improvement on the SNR performance, first the quantization operator is modeled by a deterministic polynomial function. The coefficients in the polynomial function are defined in such a way that the total energy difference between the quantization function and the polynomial function is minimized subject to a specification on the upper bound of the absolute difference. This problem is actually a semi-infinite programming problem and our recently proposed dual parameterization method is employed for finding the globally optimal solution. Second, the condition for improving the SNR performance is derived via a frequency domain formulation. To optimally design the periodic code such that the SNR performance is maximized, a modified gradient descent method that can avoid the obtained solution to be trapped in a locally optimal point and guarantee its convergence is proposed. Computer numerical simulation results show that the proposed system could achieve a significant improvement compared to existing systems such as the conventional system without multiplying to the periodic code, the system with an additive dithering and a first order sigma delta modulator.